Double chamber syringes typically include a first chamber having a powdered drug therein and a second chamber having a diluting substance. Before using the syringe, the powdered drug and the diluting substance must be mixed. The first and second chambers respectively containing the powdered drug and diluting substance are usually separated by a septum or the like which is adapted to be breached by a needle or the like located in the internal mechanism of the syringe. Therefore, prior to injection, the chambers are moved relative to each other and an internally located pin is forced into the septum causing the same to be breached. As a result, the diluting substance of the first chamber is caused to mix with the powdered drug. Thereafter, the syringe is used to inject the mixture into the patient.
Because the septums or the like are breached with a sharply pointed instrument, small parts of the septum, usually formed from rubber, are caused to leach into the mixture. Consequently, the mixture having the rubber contaminant is injected into a patient and tests have shown that such contaminants can be physically harmful to humans. A plurality of differently designed syringes are available which use a sharp instrument for breaching a septum for the mixture of substances to be injected into a patient. None of these devices consider the possibility of or take measures to forestall contamination via particles broken from septums.
U.S. Pat. No. 4,886,495 to Reynolds discloses a pre-filled syringe for use with one or two component medicaments which uses a vial containing a medicament, or at least one component of a medicament, wherein the vial has an open bottom which engages a piston. The piston is coupled with a plunger and an adapter cap having an internal needle. An external connection for a needle is placed over a cap on the vial, causing the assembly to be converted into a pre-filled syringe. The piston has an axial passage closed by a resealable septum. A separate diluent stored in a flexible capsule may be introduced into the vial through the piston by a double ended needle mounted on a further cap attached to the capsule. The further cap is coupled within the tubular interior of the plunger so that the double ended needle penetrates the septum in the piston. The capsule is pushed forward onto the double ended needle when its contents are to be expelled into the vial. The capsule and its cap are then removed and discarded. Because a sharp pointed needle is used for breaching the septum, as discussed above, contaminants comprised of particles of the septum are prone to enter the medicament, possibly resulting in harm to the medicament user.
U.S. Pat. No. 4,702,737 discloses a dual dose syringe. The syringe includes a barrel comprising a plurality of telescoping sections of progressively decreasing diameter. A puncturable fluid tight membrane extends across the forward end of each barrel section, with exception to the first, and divides the interior of the barrel into a plurality of separate fluid receiving chambers. Each of the chambers may contain a different fluid medication. A plunger is slidably mounted in the last barrel section and extends exteriorly therefrom. At the forward end of the syringe is a hollow needle, which extends through a needle receiving tubular conduit at the forward end of the first barrel section so that the needle is disposed partly inside and partly outside the barrel. Both ends of the needle are sharply pointed. The inner end of the needle is adapted to puncture the membrane so that as each chamber in the barrel is emptied, the next chamber is placed in communication with the needle. As indicated above, such puncturing of the membrane can cause particles of the membrane to leach into the mixture to be injected. Accordingly, the mixture with the contaminants are injected into the medication receiver, possibly having ill effects.
There exist a need, therefore, for a syringe having a septum or the like for separating different components of a medication which is breachable via the internal mechanism of the syringe yet does not risk contamination of the medication in the syringe with small particles of the septum.